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From kant kodali <kanth...@gmail.com>
Subject Re: why spark driver program is creating so many threads? How can I limit this number?
Date Tue, 01 Nov 2016 18:25:27 GMT
AH!!! Got it! Should I use 2.0.1 then ? I don't see 2.1.0

On Tue, Nov 1, 2016 at 10:14 AM, Shixiong(Ryan) Zhu <shixiong@databricks.com
> wrote:

> Dstream "Window" uses "union" to combine multiple RDDs in one window into
> a single RDD.
>
> On Tue, Nov 1, 2016 at 2:59 AM kant kodali <kanth909@gmail.com> wrote:
>
>> @Sean It looks like this problem can happen with other RDD's as well. Not
>> just unionRDD
>>
>> On Tue, Nov 1, 2016 at 2:52 AM, kant kodali <kanth909@gmail.com> wrote:
>>
>> Hi Sean,
>>
>> The comments seem very relevant although I am not sure if this pull
>> request https://github.com/apache/spark/pull/14985 would fix my issue? I
>> am not sure what unionRDD.scala has anything to do with my error (I don't
>> know much about spark code base). Do I ever use unionRDD.scala when I call
>> mapToPair or ReduceByKey or forEachRDD?  This error is very easy to
>> reproduce you actually don't need to ingest any data to spark streaming
>> job. Just have one simple transformation consists of mapToPair, reduceByKey
>> and forEachRDD and have the window interval of 1min and batch interval of
>> one one second and simple call ssc.awaitTermination() and watch the
>> Thread Count go up significantly.
>>
>> I do think that using a fixed size executor service would probably be a
>> safer approach. One could leverage ForJoinPool if they think they could
>> benefit a lot from the work-steal algorithm and doubly ended queues in the
>> ForkJoinPool.
>>
>> Thanks!
>>
>>
>>
>>
>> On Tue, Nov 1, 2016 at 2:19 AM, Sean Owen <sowen@cloudera.com> wrote:
>>
>> Possibly https://issues.apache.org/jira/browse/SPARK-17396 ?
>>
>> On Tue, Nov 1, 2016 at 2:11 AM kant kodali <kanth909@gmail.com> wrote:
>>
>> Hi Ryan,
>>
>> I think you are right. This may not be related to the Receiver. I have
>> attached jstack dump here. I do a simple MapToPair and reduceByKey and  I
>> have a window Interval of 1 minute (60000ms) and batch interval of 1s (
>> 1000) This is generating lot of threads atleast 5 to 8 threads per
>> second and the total number of threads is monotonically increasing. So just
>> for tweaking purpose I changed my window interval to 1min (60000ms) and
>> batch interval of 10s (10000) this looked lot better but still not ideal
>> at very least it is not monotonic anymore (It goes up and down). Now my
>> question  really is how do I tune such that my number of threads are
>> optimal while satisfying the window Interval of 1 minute (60000ms) and
>> batch interval of 1s (1000) ?
>>
>> This jstack dump is taken after running my spark driver program for 2
>> mins and there are about 1000 threads.
>>
>> Thanks!
>>
>>
>>
>>

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